1. Field of the Invention
The invention relates to an ultrasonic test head for testing flaws in a workpiece, and to a method for its operation.
Crack-type flaws in a workpiece can have a varying depth and a varying orientation relative to the surface of the workpiece. In order to enable detection of all of the possible flaws in non-destructive ultrasonic testing, it is necessary to use a plurality of ultrasonic test heads, each of which is suitable for different types of flaws, and those ultrasonic test heads must be employed in successive measurements.
Test heads which are known from the publication entitled: "Materialprufung 28"[Materials Testing 28] 1986, pp. 20-24, each contain two ultrasonic transducer arrays operated in the transmit/receive mode. Those ultrasonic transducer arrays are coupled to wedge attachments that are replaceable in a manner adapted to the particular testing problem involved.
Although with those known configurations high flexibility with respect to the direction at which sound enters can be attained, nevertheless different test heads must be used, in order to fit the depth of the flaw. The replacement of the test heads or prism wedges and the attendant necessity of repeating the measurements several times by passing over the entire testing zone again is time-consuming and should be avoided, especially in surroundings that can cause radiation exposure to the workers doing the testing. Additionally, correlating the results of tests obtained in the various measurements is more difficult.